洪潮影响下潭江流域安全行洪阈值研究

Research on safety threshold of flood discharge in the Tanjiang River Basin under impact of floods and tides

为研究洪潮叠加影响下潭江流域下游感潮河段河道洪水演进动态与行洪能力,构建了一维水动力模型,通过多组洪潮组合工况模拟计算,量化了不同潮位、控制水位、持续泄流时间下潭江流域控制性节点安全行洪阈值以及涨落潮情形下的行洪能力,揭示了洪潮影响下潭江流域水文变化规律,并结合随机森林模型,绘制了高精度安全行洪阈值图谱。结果表明:以潮动力为主的潭江流域下游感潮河段,干流水位主要受下游潮位影响,高潮位的洪潮顶托效应更为强烈,安全行洪阈值受潮位和泄流时间影响;落潮时段行洪能力较涨潮时段明显增强,且落潮时段行洪能力与控制断面水位基本呈线性变化。

To study the dynamics of flood propagation and discharge capacity in the downstream tidal river section of the Tanjiang River Basin under flood and tide overlapping conditions,a one-dimensional hydrodynamic model was constructed to quantify the safety threshold of flow discharge at key control node of the Tanjiang River Basin and flood discharge capacity during tidal cycles under various tidal levels,control water levels,and discharge durations,and reveal the hydrological patterns of the Tanjiang River Basin under combined influences of floods and tides through simulation and calculation in multiple scenarios.Then,a high-precision safe flood discharge threshold map was obtained by using the the random frest model.The results indicate that in the downstream tidal river section of the Tanjiang River Basin dominated by tidal dynamics,the water level in the main channel is primarily affected by downstream tidal level,with the flood-tide backwater effect being more pronounced in high tides,and the safe threshold of flood discharge is affected by both tidal level and discharge duration.The flood discharge capacity in ebb tide period is significantly higher than that in flood tide period,and the flood discharge capacity in ebb tide period generally exhibits a linear variation with the water level of control section.